Put the strawberries in a blender. In a small saucepan, combine the water with the sugar and cook over moderate heat, stirring occasionally, until the sugar dissolves. Pour the hot syrup over the strawberries and add the lemon zest. Blend to a smooth puree.
Pass the puree through a fine strainer into a large glass baking dish. Place in the freezer. Stir the puree every 20 minutes with a fork, until fine frozen shards have formed. Alternatively, freeze the puree overnight and let stand at room temperature for 5 minutes, then crush with a potato masher until it resembles coarse ice. Serve the granité in chilled glasses or cups.
The granité can be frozen for 2 days.
One Serving Calories 78 kcal, Total Fat 0.2 gm, Saturated Fat 0 gm, Protein 0 gm, Carbohydrates 20 gm.